The everyday medicines that can fuel obesity

Drugs handed out for common ailments such as diabetes, epilepsy, depression, heart disease and high blood pressure are partly responsible for Britain's obesity epidemic, they claim.

Scientists who analysed data on more than 25,000 patients found some put on as much as 22lb a year because of their medication.

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Some of the drugs, such as those prescribed for heart disease and arthritis, are known to increase appetite or slow down a patient's metabolic rate, thus promoting weight gain.

But researchers from Glasgow University and Glasgow Royal Infirmary said more studies were needed to explain exactly why others, such as those for mental illnesses, also caused patients to put on weight.

The scientists analysed drugs routinely used by doctors to treat chronic diseases affecting tens of thousands.

Olanzapine and clozapine, two drugs used for psychiatric conditions, resulted in the most weight gain, with some putting on up to 22lb in a year.

Insulin for type 2 diabetes was found to increase weight by up to 13lb per year, while some drugs for epilepsy added more than 12lb.

Some medicines for depression added up to 8lb, while beta-blockers and other drugs used to treat high blood pressure and heart disease added between 5lb and 3lb.

In the UK around 2.6million have been diagnosed with coronary heart disease, while more than 400,000 have epilepsy and around 1.3million have type 1 or type 2 diabetes.

In Scotland alone, the number of prescriptions dispensed for betablockers and tricyclic anti-depressants between 2004 and 2005 exceeded one million and two million respectively, the report said.

As a consequence, the researchers said, it was likely that prescription drugs were partly responsible for the increasing problem of obesity.

They said unexpected weight gain could be a reason why some patients stopped taking their medicine and added that doctors should discuss with patients the risk of weight gain before they start treatment.